package xyj.sparrow.client.proxy;

import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.core.env.Environment;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternUtils;
import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
import org.springframework.core.type.classreading.MetadataReader;
import org.springframework.core.type.classreading.MetadataReaderFactory;
import org.springframework.util.ClassUtils;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import xyj.sparrow.client.annotation.Service;
import xyj.sparrow.client.service.IRegisterService;

import java.io.IOException;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

@Slf4j
public class HandlerBeanDefinitionRegistry implements BeanDefinitionRegistryPostProcessor, ResourceLoaderAware,
        ApplicationContextAware {
    private static final String DEFAULT_RESOURCE_PATTERN = "/**/*.class";
    private MetadataReaderFactory metadataReaderFactory;
    private ResourcePatternResolver resourcePatternResolver;
    private ApplicationContext applicationContext;
    private static Set<Class<?>> beanClassSet;

    public static Set<Class<?>> listService() {
        return beanClassSet;
    }

    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        Map<String, Object> annotatedBeans = applicationContext.getBeansWithAnnotation(SpringBootApplication.class);
        String packageName = annotatedBeans.isEmpty() ? null :
                annotatedBeans.values().toArray()[0].getClass().getName();

        //这里一般我们是通过反射获取需要代理的接口的clazz列表
        //比如判断包下面的类，或者通过某注解标注的类等等
        assert packageName != null;
        Set<Class<?>> beanClazzs = scannerPackages(packageName.substring(0, packageName.lastIndexOf(".")));
        beanClassSet = beanClazzs;
        for (Class beanClazz : beanClazzs) {
            setBeanClass(registry, beanClazz);
        }
        setBeanClass(registry, IRegisterService.class);
    }

    private void setBeanClass(BeanDefinitionRegistry registry, Class beanClazz) {
        BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(beanClazz);
        GenericBeanDefinition definition = (GenericBeanDefinition) builder.getRawBeanDefinition();

        //在这里，我们可以给该对象的属性注入对应的实例。
        //比如mybatis，就在这里注入了dataSource和sqlSessionFactory，
        // 注意，如果采用definition.getPropertyValues()方式的话，
        // 类似definition.getPropertyValues().add("interfaceType", beanClazz);
        // 则要求在FactoryBean（本应用中即ServiceFactory）提供setter方法，否则会注入失败
        // 如果采用definition.getConstructorArgumentValues()，
        // 则FactoryBean中需要提供包含该属性的构造方法，否则会注入失败
        definition.getConstructorArgumentValues().addGenericArgumentValue(beanClazz);

        //注意，这里的BeanClass是生成Bean实例的工厂，不是Bean本身。
        // FactoryBean是一种特殊的Bean，其返回的对象不是指定类的一个实例，
        // 其返回的是该工厂Bean的getObject方法所返回的对象。
        definition.setBeanClass(RpcFactoryBean.class);

        //这里采用的是byType方式注入，类似的还有byName等
        definition.setAutowireMode(GenericBeanDefinition.AUTOWIRE_BY_TYPE);
        registry.registerBeanDefinition(beanClazz.getSimpleName(), definition);
    }


    /**
     * 根据包路径获取包及子包下的所有类
     *
     * @param basePackage basePackage
     * @return Set<Class < ?>> Set<Class<?>>
     */
    private Set<Class<?>> scannerPackages(String basePackage) {
        Set<Class<?>> set = new LinkedHashSet<>();
        String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
                resolveBasePackage(basePackage) + DEFAULT_RESOURCE_PATTERN;
        try {
            Resource[] resources = this.resourcePatternResolver.getResources(packageSearchPath);
            for (Resource resource : resources) {
                if (resource.isReadable()) {
                    MetadataReader metadataReader = this.metadataReaderFactory.getMetadataReader(resource);
                    String className = metadataReader.getClassMetadata().getClassName();
                    Class<?> clazz;
                    try {
                        clazz = Class.forName(className);
                        Service anno = clazz.getAnnotation(Service.class);
                        if (anno != null) {
                            set.add(clazz);
                        }

                    } catch (ClassNotFoundException e) {
                        e.printStackTrace();
                    }
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return set;
    }

    protected String resolveBasePackage(String basePackage) {
        return ClassUtils.convertClassNameToResourcePath(this.getEnvironment().resolveRequiredPlaceholders(basePackage));
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {

    }


    @Override
    public void setResourceLoader(ResourceLoader resourceLoader) {
        this.resourcePatternResolver = ResourcePatternUtils.getResourcePatternResolver(resourceLoader);
        this.metadataReaderFactory = new CachingMetadataReaderFactory(resourceLoader);
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    private Environment getEnvironment() {
        return applicationContext.getEnvironment();
    }
}